Chemistry is the category where the data matters more than the arithmetic. Adding up a molar mass is primary school addition; knowing what to add is not, because the standard atomic weights come from one body — the IUPAC Commission on Isotopic Abundances and Atomic Weights — and get revised as measurements improve, gadolinium, lutetium and zirconium as recently as 2024. Fourteen elements have no single weight at all. Hydrogen, carbon, oxygen and eleven others vary in isotopic composition between natural sources, so the Commission publishes an interval for them and a separate abridged value for anyone who needs one number to multiply. Every tool here names which of the two it used, because a molar mass quoted to five figures from a weight known to three is a false precision that looks exactly like a real one.
Tools in this category
Molar mass calculator
Type a formula — brackets, nesting and hydrates included — for its molar mass in g/mol and how much of that mass each element contributes.
Dilution calculator
C₁V₁ = C₂V₂ solved for whichever value you leave at zero, with the volume of solvent to add and the dilution factor worked out alongside.
Solution concentration calculator
Weigh out a solute, give the volume and the molar mass, and get the molarity, the grams per litre and the mass percent of the solution.
Suggest a tool
Tell us what is missing and where its numbers should come from.
What should it convert, calculate or generate, and where would the authoritative numbers come from? A link to the standard or publication that defines them is the most useful thing you can send.
Opens your mail app with this page already filled in.
How these tools are built
Every tool in this category runs entirely in your browser: there is no upload, no account and no request to a server once the page has loaded. The numbers behind them are transcribed from the organisation that defines them — NIST for units, the W3C for web formats, the WHO for health measures — and each page names its source next to the formula. A tool whose reference values stop reproducing fails the build and does not ship, which is the whole reason the catalogue grows slowly.